Characterization of implanted semiconductors by means of white-beam and plane-wave synchrotron topography

Abstract

Al(x)Ga(1-x)As epitaxic layers, with x = 0.43 and GaAs single crystals implanted with various doses of high-energy Se and Si ions, and silicon single crystals implanted with high-energy light ions were studied by means of different X-ray diffraction methods employing either a strongly limited white beam or a highly collimated monochromatic beam. The methods provided complementary characterization of lattice parameter changes and lattice deformation in the implanted layers. The synchrotron rocking curves recorded with a small-diameter beam provided a very good separation of interference maxima and enabled determination of the strain profile. A characteristic difference in strain depth distributions between the implanted A(III)B(V) compounds and silicon was noticed. Ion implantation in A(III)B(V) compounds produced a relatively thick layer with an almost constant and distinctly increased lattice parameter in regions close to the surface, whereas, in the case of silicon, shot-through layers with almost unchanged lattice spacing were observed. Other important information obtained from the synchrotron micro-Laue pattern was that the interference fringes caused by crystal curvature or strain gradient are located in the plane of diffraction, while parts of the Laue spot corresponding to the deformed regions are usually displaced.